When children come of a certain age and become suspicious of all of the creepy, invasive, magical, mysterious actions that Santa is supposed to do, but their fervently passionate holiday crazed parents do instead.
"Oh all of the big presents are coming via drone this year from Amazon being as Timmy as become Santaspicious"
when you're holding up your phone and making faces at it, as though you are taking a selfie, but you're really taking a picture of the person across from you or the wall or anything else that seems interesting but you don't want to be caught dead taking a picture of.
This action is often made more convincing by wiggling the eyebrows or opening the mouth, to pretend you're trying to get a Snapchat filter to work.
FRIEND A: "Did you just take a stealthie of me?"
FRIEND B (turning phone around): "no I was just using snapchat's new filter, see?"